The purpose of this study is to examine the profitability of variable rate phosphorus application on a rotation of rice (Oryza sativa) and soybeans (Glycine max) on fields comprised of clay and silt loam soils. Phosphorus was chosen because 1) farmers have recently been advised of the benefit of phosphorus applications on rice as well as soybeans, 2)recommended phosphorus application rates vary greatly between clay and silt loam soils and across rice and soybeans, and 3) the residual effects of phosphorus applications in a crop rotation affect the appropriateness of variable rate technology (VRT). A three phase simulation, regression and mathematical optimization analysis was conducted to determine within a ten year planning horizon the conditions under which the profitability of variable rate phosphorus applications exceeded the profitability of uniform rate technology. Results showed that in general, VRT is not profitable when fields are comprised of only the three studied silt loam soils. However, VRT was found to be profitable in most cases when even small percentages of clay were added to the soil mixin the field. Adoption will likely also be a function off arm size. Farmers earning relatively small returns to VRT on a small area are not as likely to adopt the technology as larger operations with similar per hectare returns.
Popp, Jennie; Griffin, Terry W.; Popp, Michael P.; and Baker, William H.
"Profitability of Variable Rate Phosphorus in a Two Crop Rotation,"
Journal of the Arkansas Academy of Science: Vol. 56
, Article 20.
Available at: http://scholarworks.uark.edu/jaas/vol56/iss1/20